Still's disease, severe thrombocytopenia, and acute hepatitis associated with acute parvovirus B19 infection

Disseminated Human Parvovirus B19 Infection Induced Multiple Organ Dysfunction Syndrome in an Adult Patient With Alcoholic Hepatitis Complicated by Hemolytic Anemia: A Case Report and Literature Review

Background

Human parvovirus B19 (B19) can cause acute hepatitis and is attributed to the high mortality of alcoholic hepatitis (AH). B19 infection is generally self-healing in previously healthy people, but it can cause fatal effects in some high-risk groups and increase its virulence and infectivity. Disseminated B19 infection-induced multiple organ dysfunction syndrome (MODS) in patients with AH has not been reported yet. Here, we described B19 viremia in an adult patient with AH accompanied by hemolytic anemia (HA), leading to disseminated infection and secondary MODS, as well as self-limiting B19 infections in seven nurses caring for him. Meanwhile, we reviewed the literature on AH and B19 infection.

Case Presentation

A 43-year-old male patient with AH accompanied by HA was transferred to the Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China, on March 31, 2021. After supportive treatment, his transaminase and bilirubin levels were reduced, but his anemia worsened. He received a red blood cell (RBC) infusion on April 9 for hemoglobin (Hb) lower than 6 g/dl. On April 13, he suddenly had a high fever. Under empirical anti-infection, his high fever dropped and maintained at a low fever level; however, his anemia worsened. On April 25, he was transferred to the medical intensive care unit (MICU) due to severe pneumonia, acute respiratory distress syndrome (ARDS), acute aplastic crisis (AAC), and hemophagocytic syndrome (HPS), which were subsequently confirmed to be related to B19 infection. After methylprednisolone, intravenous immunoglobulin (IVIG), empirical anti-infection, and supportive treatment, the lung infection improved, but hematopoietic and liver abnormalities aggravated, and systemic B19 infection occurred. Finally, the patient developed a refractory arrhythmia, heart failure, and shock and was referred to a local hospital by his family on May 8, 2021. Unfortunately, he died the next day. Fourteen days after he was transferred to MICU, seven nurses caring for him in his first two days in the MICU developed self-limiting erythema infectiosum (EI).

Conclusions

B19 infection is self-limiting in healthy people, with low virulence and infectivity; however, in AH patients with HA, it can lead to fatal consequences and high contagion.

The role of viral infections in the development of autoimmune diseases

The exact aetiology of most autoimmune diseases remains unknown, nonetheless, several factors contributing to the induction or exacerbation of autoimmune reactions have been suggested. These include the genetic profile and lifestyle of the affected individual in addition to environmental triggers such as bacterial, parasitic, fungal and viral infections. Infections caused by viruses usually trigger a potent immune response that is necessary for the containment of the infection; however, in some cases, a failure in the regulation of this immune response may lead to harmful immune reactions directed against the host's antigens. The autoimmune attack can be carried out by different arms and components of the immune system and through different possible mechanisms including molecular mimicry, bystander activation, and epitope spreading among others. In this review, we examine the data available for the involvement of viral infections in triggering or exacerbating autoimmune diseases in addition to discussing the mechanisms by which these viral infections and the immune pathways they trigger possibly contribute to the development of autoimmunity.

Recent Advances in Replication and Infection of Human Parvovirus B19

Parvovirus B19 (B19V) is pathogenic to humans and causes bone marrow failure diseases and various other inflammatory disorders. B19V infection exhibits high tropism for human erythroid progenitor cells (EPCs) in the bone marrow and fetal liver. The exclusive restriction of B19V replication to erythroid lineage cells is partly due to the expression of receptor and co-receptor(s) on the cell surface of human EPCs and partly depends on the intracellular factors essential for virus replication. We first summarize the latest developments in the viral entry process and the host cellular factors or pathways critical for B19V replication. We discuss the role of hypoxia, erythropoietin signaling and STAT5 activation in the virus replication. The B19V infection-induced DNA damage response (DDR) and cell cycle arrest at late S-phase are two key events that promote B19V replication. Lately, the virus infection causes G2 arrest, followed by the extensive cell death of EPCs that leads to anemia. We provide the current understanding of how B19V exploits the cellular resources and manipulate pathways for efficient virus replication. B19V encodes a single precursor mRNA (pre-mRNA), which undergoes alternate splicing and alternative polyadenylation to generate at least 12 different species of mRNA transcripts. The post-transcriptional processing of B19V pre-mRNA is tightly regulated through cis-acting elements and trans-acting factors flanking the splice donor or acceptor sites. Overall, in this review, we focus on the recent advances in the molecular virology and pathogenesis of B19V infection.

Human Parvoviruses

Parvovirus B19 (B19V) and human bocavirus 1 (HBoV1), members of the large Parvoviridae family, are human pathogens responsible for a variety of diseases. For B19V in particular, host features determine disease manifestations. These viruses are prevalent worldwide and are culturable in vitro, and serological and molecular assays are available but require careful interpretation of results. Additional human parvoviruses, including HBoV2 to -4, human parvovirus 4 (PARV4), and human bufavirus (BuV) are also reviewed. The full spectrum of parvovirus disease in humans has yet to be established. Candidate recombinant B19V vaccines have been developed but may not be commercially feasible. We review relevant features of the molecular and cellular biology of these viruses, and the human immune response that they elicit, which have allowed a deep understanding of pathophysiology.

The role of parvovirus B19 in the pathogenesis of autoimmunity and autoimmune disease

Human parvovirus B19 is a single-stranded DNA virus which preferentially targets the erythroblasts in the bone marrow. B19 infection commonly causes erythema infectiosum, arthralgia, fetal death, transient aplastic crisis in patients with shortened red cell survival, and persistent infection in people who are immunocompromised. Less common clinical manifestations include atypical skin rashes, neurological syndromes, cardiac syndromes, and various cytopenias. B19 infection has also been associated with development of a variety of different autoimmune diseases, including rheumatological, neurological, neuromuscular, cardiovascular, haematological, nephrological and metabolic. Production of a variety of autoantibodies has been demonstrated to occur during B19 infection and these have been shown to be key to the pathogenesis of the particular disease process in a significant number of cases, for example, production of rheumatoid factor in cases of B19-associated rheumatoid arthritis and production of anti-glutamic acid decarboxylase (GAD) in patients with B19-associated type 1 diabetes mellitus. B19 infection has also been associated with the development of multiple autoimmune diseases in 12 individuals. Documented mechanisms in B19-associated autoimmunity include molecular mimicry (IgG antibody to B19 proteins has been shown to cross react with a variety of recognised human autoantigens, including collagen II, keratin, angiotensin II type 1 receptor, myelin basic protein, cardiolipin, and platelet membrane glycoprotein IIb/IIIa), B19-induced apoptosis with presentation of self-antigens to T lymphocytes, and the phospholipase activity of the B19 unique VP1 protein.

Severe hyperferritinemia--a clue for severe hepatitis in a patient with adult-onset Still's disease

A 19-year old previously healthy man developed the adult-onset Still's disease (AOSD) with high ferritin levels. Corticosteroids induced clinical remission with resolution of fever, arthritis, and rash. While tapering corticosteroids, the patient developed severe liver enzymes elevation, very high ferritin levels and, subsequently, acute liver failure. After other causes of liver disease (infections, metabolic, autoimmune hepatitis, lymphoma, and hemophagocytosis) were excluded, severe hepatitis was attributed to AOSD itself. Cyclosporine induced rapid normalization of liver enzymes and reduction in ferritin levels. Severe hepatitis and very high ferritin levels could be the only manifestation of disease activity in AOSD; therefore, monitoring of liver enzymes and ferritin levels is recommended even after resolution of the clinical symptoms of AOSD. Prompt initiation of cyclosporine can improve liver function and prevent progression to liver failure.

Parvovirus b19 associated hepatitis

Parvovirus B19 infection can present with myriads of clinical diseases and syndromes; liver manifestations and hepatitis are examples of them. Parvovirus B19 hepatitis associated aplastic anemia and its coinfection with other hepatotropic viruses are relatively underrecognized, and there is sufficient evidence in the literature suggesting that B19 infections can cause a spectrum of liver diseases from elevation of transaminases to acute hepatitis to fulminant liver failure and even chronic hepatitis. It can also cause fatal macrophage activation syndrome and fibrosing cholestatic hepatitis. Parvovirus B19 is an erythrovirus that can only be replicate in pronormoblasts and hepatocytes, and other cells which have globosides and glycosphingolipids in their membrane can also be affected by direct virus injury due to nonstructural protein 1 persistence and indirectly by immune mediated injury. The virus infection is suspected in bone marrow aspiration in cases with sudden drop of hemoglobin and onset of transient aplastic anemia in immunosuppressed or immunocompetent patients and is confirmed either by IgM and IgG positive serology, PCR analysis, and in situ hybridization in biopsy specimens or by application of both. There is no specific treatment for parvovirus B19 related liver diseases, but triple therapy regimen may be effective consisting of immunoglobulin, dehydrohydrocortisone, and cyclosporine.

[An exceptional cause of acute hepatitis in an adult: parvovirus B19]

There are multiple causes of hepatitis. The most frequent etiologies are viral, usually hepatitis A, B and C viruses. However, other, non-hepatotropic viruses can cause this disease, including parvovirus B19. We present a case of acute hepatitis due to parvovirus B19, as well as a review of the epidemiological, clinical, diagnostic and therapeutic features of this entity.

Adult-onset Still's disease: pathogenesis, clinical manifestations and therapeutic advances

Adult-onset Still's disease (AOSD) is a rare, systemic inflammatory disease of unknown aetiology, characterized by daily high spiking fevers, evanescent rash and arthritis. Our objective was to review the most recent medical literature regarding advances in the understanding of disease pathogenesis, diagnosis and treatment. There is no single diagnostic test for AOSD, and diagnosis is based on clinical criteria and usually necessitates the exclusion of infectious, neoplastic and autoimmune diseases. Laboratory tests are nonspecific and reflect heightened immunological activity with leukocytosis, elevated acute phase reactants and, in particular, extremely elevated serum ferritin levels. Abnormal serum liver function tests are common, while rheumatoid factor and antinuclear antibodies are usually absent. Recent studies of the pathogenesis of the disease have suggested an important role for cytokines. Interleukin (IL)-1, IL-6 and IL-18, macrophage colony-stimulating factor, interferon-gamma and tumour necrosis factor (TNF)-alpha are all elevated in patients with AOSD. Prognosis depends on the course of the disease and tends to be more favourable when systemic symptoms predominate. Treatment includes the use of corticosteroids, often in combination with immunosuppressants (e.g. methotrexate, gold, azathioprine, leflunomide, tacrolimus, ciclosporin and cyclophosphamide) and intravenous immunoglobulin. Biological agents (e.g. anti-TNFalpha, anti-IL-1 and anti-IL-6) have been successfully used in refractory cases. Further progress has been hampered by the rarity and heterogeneity of the disease, which has not permitted the execution of randomized controlled studies.

Severe thrombocytopenia associated with acute hepatitis E virus infection

We describe here what is, to the best of our knowledge, the third reported case of severe thrombocytopenia associated with acute hepatitis E virus infection. The patient was a 72-year-old French woman. It seems likely that the cause of the thrombocytopenia was acute hepatitis E virus infection, possibly occurring via an immune mechanism. No complications were noted, in contrast to the two previous reports.

Adult-onset Still's disease: can recent advances in our understanding of its pathogenesis lead to targeted therapy?

Adult-onset Still's disease is a rare systemic inflammatory disease of unknown etiology, characterized by daily high, spiking fevers, evanescent rash, and arthritis. There is no single diagnostic test for adult-onset Still's disease; rather, the diagnosis is based on clinical criteria and necessitates the exclusion of infectious, neoplastic, and other 'autoimmune' diseases. Proinflammatory cytokines such as interleukin (IL)-1, IL-6, and IL-18, interferon-gamma, tumor necrosis factor, and macrophage colony-stimulating factor are elevated in patients with adult-onset Still's disease and are thought to have a major role in the pathogenesis of the disease. Treatment consists of nonsteroidal anti-inflammatory drugs, corticosteroids, immunosuppressants (methotrexate, gold, azathioprine, leflunomide, cyclosporin, and cyclophosphamide), intravenous immunoglobulin, and cytokine (tumor necrosis factor, IL-1 and IL-6) inhibitors. Recent advances in basic immunology have enhanced our ability to hinder the pathogenic mechanisms associated with adult-onset Still's disease and have led to a paradigm shift where targeted treatments have an increasingly important role.

[Current concepts on the physiopathology of adult-onset Still's disease]

PURPOSE

Adult-onset Still's disease (AOSD) is a rare systemic inflammatory disorder of unknown origin. It is characterized by hectic fever, evanescent rash, polyarthralgias or polyarthritis, sore throat, hepatosplenomegaly, lymphadenopathy, polynuclear leukocytosis, liver cytolysis, and high serum level of ferritin with low glycosylated fraction.

CURRENT KNOWLEDGE AND KEY POINTS

An increased serum level of ferritin, IL-8, IL-6, IL-18 and TNF-alpha indicates that macrophages are highly activated in AOSD. Interleukin 18 (IL-18) seems to be a key cytokine in the pathogenesis of AOSD. Serum IL-18 levels are increased in AOSD patients compared to other systemic inflammatory diseases such as rheumatoid arthritis and they are well correlated with serum ferritin levels and disease activity. IL-18 could cause acute liver injury and arthritis. Macrophages could be activated by infectious agents such as viruses and by an inadequate control of T cell response secondary to depressed Natural Killer lymphocyte function, similarly to that observed in systemic juvenile idiopathic arthritis. Sustained macrophage activation can lead to the hemophagocytic syndrome, a severe complication of both AOSD and systemic juvenile idiopathic arthritis.

FUTURE PROSPECTS

Cytotoxic cell functions should be probably studied in AOSD as they were in the hemophagocytic syndrome and systemic juvenile idiopathic arthritis because AOSD, characterised by a marked macrophage activation may be related to an immunological deficiency.

[Diagnosis, progression and prognosis, aetiology and treatment of adult-onset Still's disease]

DIAGNOSTIC DOUBTS: Despite an increased awareness of the clinical features of the disease, adult onset Still's disease (AOSD) remains a diagnosis of exclusion. Many diagnostic criteria have been published, and the most popular are those proposed by Yamaguchi, even though they do not consider the presence of hyperferritinemia or the decrease of it glycosylated fraction, and they include exclusion criteria that are difficult to satisfy. UNPREDICTABLE PROGRESSION: Three evolutive forms have been described: monocyclic, intermittent with articular and/or systemic flares, chronic, usually in the form of chronic polyarthritis. Vital prognosis is sometimes compromised by severe systemic manifestations or the occurrence of amyloidosis, whilst destructive polyarthritis, particularly common in the chronic form, may compromise the function. The aetiology of AOSD remains unknown. THERAPEUTIC UNCERTAINTIES: Treatment is largely empirical in the absence of randomized clinical trials because of the rarity of the disease. Nonsteroidal anti-inflammatory drugs could be used in moderately severe forms of the disease, but they rare rarely sufficient. Around 80% of the patients require corticosteroids. Among the disease modifying drugs, methotrexate still remains the most effective. The role of the new anti-TNF molecules remains to be specified.

Manifestations systémiques des infections à Parvovirus B19

PURPOSE

Parvovirus B19 (B19) causes many clinical disorders, of which the most common are erythema infectiosum, aplastic crisis complicating chronic hemolytic anemia, and hydrops fetalis. In young adults, the skin eruption caused by B19 is accompanied by polyarthritis and polyarthralgia in 60% of the cases. Rheumatoid factors and other antibodies including antinuclear antibodies, anti-ADN, and antiphospholipids can be produced in the wake of B19 infection.

CURRENT KNOWLEDGE AND KEY POINTS

These features may simulate systemic diseases as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) (lupus-like eruption over the cheeks, cytopenia, etc.) or vasculitis (purpura, renal involvement). In addition, there have been a few reports of SLE, vasculitis and other connective tissue diseases developing shortly after a B19 infection associated with virus clearance suggesting that B19 can act as a trigger of systemic disease. However, studies in large series indicate that in fact B19 is probably an extremely rare cause of RA, SLE or vasculitis.

FUTURE PROSPECTS AND PROJECTS

In fundamental studies B19 interacts with inflammatory cells by regulation of cytokines. More recently, two studies suggest that viral infection due to B19 may affect the course of SLE, leading to specific biological subsets. These preliminary findings require confirmation to elucidate the significance of the presence of B19 in systemic disease.

Collapsing glomerulopathy in adult still's disease

Idiopathic collapsing glomerulopathy is a clinically and pathologically distinct variant of focal segmental glomerulosclerosis characterized clinically by a male and Afro-Caribbean racial predominance, proteinuria (often nephrotic range), and rapid progression to end-stage renal failure. Pathologically, the typical changes are global glomerular collapse leading to obliteration of glomerular capillary lumina, hypertrophy and hyperplasia of podocytes, and severe tubulointerstitial changes. A secondary form with almost identical pathologic features is described in association with human immunodeficiency virus infection. We describe a female patient who presented with multisystemic manifestations, including high spiking fever, arthralgias, lymphadenopathy, striking hyperferritinemia, and impaired renal function with proteinuria. Renal biopsy showed classic collapsing glomerulopathy. A diagnosis of adult Still's disease was made on the basis of Yamaguchi's criteria. The patient was treated with steroids, resulting in remission of the rheumatological condition closely paralleled by remission of proteinuria and renal function, thereby strongly suggesting a causative link between adult Still's disease and collapsing glomerulopathy in this patient. We propose that collapsing glomerulopathy ought to be considered in adult Still's disease with unexplained renal insufficiency or proteinuria.

Macrophage activation syndrome in a patient with systemic onset rheumatoid arthritis: rescue with intravenous immunoglobulin therapy

We report the case of a 7-year-old boy with systemic onset juvenile rheumatoid arthritis (JRA) who developed macrophage activation syndrome during a period of relative remission. He presented with high-grade fever, enlarged lymph nodes, acute hepatitis, severe pancytopenia, and evidence of disseminated intravascular coagulopathy. He became severely ill, with persistent mucosal bleeding, hypovolemia, and vascular instability, and he was admitted to the intensive care unit. No response was observed to treatment with high-dose intravenous corticosteroids and blood product replacements, but the patient fully recovered after the completion of two pulses of intravenous immunoglobulin. This treatment modality may be an alternative to anti-TNF-alpha and cyclosporine A for a prompt response in JRA patients with this potentially fatal condition.

Parvovirus B19 transmission by heat-treated clotting factor concentrates

BACKGROUND

Human parvovirus B19 (B19) DNA can be frequently detected in plasma-derived coagulation factor concentrates. The production of some clotting factor products includes heat treatment steps for virus inactivation, but the effectiveness of such steps for B19 inactivation is unclear. Moreover, detailed transmission case reports including DNA sequence analysis and quantification of B19 DNA from contaminated heat-treated blood components have not been provided so far. Therefore, the correlation between B19 DNA in blood components and infectivity remains unclear.

STUDY DESIGN AND METHODS

Asymptomatic B19 infections of two patients with hemophilia A were detected by anti-B19 seroconversion after administration of B19-contaminated heat-treated clotting factors. The suitability of nucleic acid sequence analysis for confirmation of B19 transmission was investigated. Furthermore, the B19 DNA level in blood components was determined and the drug administration was reviewed to calculate the amount of inoculated B19 DNA.

RESULTS

Both B19 transmissions from clotting factor products could be confirmed by identical nucleic acid sequences of virus DNA from patients and blood components while sequences from unrelated controls could be differentiated. One patient received, for 4 days, a total of 180 mL vapor heat-treated prothrombin complex concentrate containing 8.6 x 10(6) genome equivalents per mL of B19 DNA. The other patient received 966 mL of low-contamination (4.0 x 10(3) genome equivalents/mL) dry heat-treated FVIII concentrate over a period of 52 days.

CONCLUSION

B19 transmissions can be confirmed by nucleic acid sequencing. However, due to the low variability of the B19 genome, a large part of the B19 genome must be analyzed. The transmissions show that the applied heat treatment procedures were not sufficient to inactivate B19 completely.

Evidence for persistence of parvovirus B19 DNA in livers of adults

Recent studies have suggested a pathogenic role of human parvovirus B19 (B19) in the development of acute fulminant liver failure in children. The hypothesis was based on the detection of B19 DNA in 8 of 10 explanted livers of children requiring liver transplantation. In the present study, explanted livers from 43 adults selected at random undergoing orthotopic liver transplantation for various reasons were examined. Pre-transplant sera were available from 40 patients of whom 35 (88%) were anti-B19 IgG-seropositive. All but one serum were negative for anti-B19 IgM antibody. By polymerase chain reaction, B19 DNA was detected in the livers of 15/35 (43%) anti-B19 IgG-positive patients, in 2/3 livers of patients with unknown anti-B19 antibody status, and in the initial transplant of an anti-B19 IgG-positive patient who underwent liver retransplantation, and whose own liver was negative for B19 DNA. In a second study group, liver and bone marrow samples from 23 autopsied adults selected at random were tested. Serum specimens were available from 22 individuals, of whom 17 (77%) were anti-B19 IgG-seropositive. All sera were negative for anti-B19 IgM antibody. B19 DNA was detected in the livers of 4/17 (24%) anti-B19 IgG-positive individuals, three of whom had also B19 DNA in their bone marrow. This is the first report demonstrating that B19 DNA is frequently present in livers of anti-B19 seropositive adults suggesting persistence of B19 in the liver. Further studies are needed to address whether B19 is an innocent bystander in the liver or whether the presence of B19 in liver is of biological and clinical significance.

Detection of human parvovirus B19 in a patient with hepatitis

Parvovirus B19 has been associated by some investigators with cases of severe hepatitis. The aim of the present study was to determine the presence of active parvovirus B19 infection among 129 Brazilian patients with non-A-E hepatitis. The patients were assayed for antibodies against parvovirus B19, IgM class, by ELISA. In IgM-positive cases, parvovirus B19 DNA was assayed by PCR in serum and liver tissue and parvovirus VP1 antigen in liver tissue was assayed by immunohistochemistry. Antibodies against parvovirus B19, IgM class, were detected in 3 (2.3%) of 129 patients with non-A-E hepatitis. Previous surgery and blood transfusions were reported by these 3 patients. One patient was a 56-year-old female with severe hepatitis, with antimitochondrial antibody seropositivity and submassive necrosis at liver biopsy, who responded to corticosteroid therapy. Strong evidence for active parvovirus B19 infection was found in this patient, with parvovirus B19 DNA being detected by PCR in liver tissue. Furthermore, parvovirus VP1 antigen was also detected in liver tissue by immunohistochemistry. The other two IgM-positive patients were chronic hepatitis cases, but active infection was not proven, since neither viral DNA nor antigen were detected in their liver tissues. This and other reports suggest a possible relation between parvovirus B19 infection and some cases of hepatitis.

Adult Still's disease associated with Mycoplasma pneumoniae infection

Adult Still's disease (ASD) is a systemic inflammatory disorder of unknown origin. Several reports have suggested a triggering infection in ASD. We describe a case of ASD associated with acute Mycoplasma pneumoniae infection. The close temporal relationship between ASD and acute infection strongly suggests that M. pneumoniae triggered ASD. We suggest that M. pneumoniae should be added to the list of infectious agents that may play a role in its etiology.

Raynaud's phenomenon as a manifestation of parvovirus B19 infection: case reports and review of parvovirus B19 rheumatic and vasculitic syndromes

Infection with human parvovirus B19 is manifested as erythema infectiosum, transient aplastic crisis, or hydrops fetalis. Rheumatic manifestations include arthropathy and various vasculitic syndromes. Isolated Raynaud's phenomenon due to parvovirus B19 has never been described. We report on 2 previously healthy sisters with new-onset Raynaud's phenomenon accompanied by severe generalized polyarthralgia. A full workup was negative, except serology for parvovirus B19, which was positive. All symptoms gradually subsided within 3-5 months, and no recurrence has been noted during the 3 years since onset. We review all the studies in the English-language literature on parvovirus B19-induced rheumatic and vasculitic syndromes. We hypothesize that the pathogenesis of Raynaud's phenomenon in our patients involved immune-mediated endothelial damage leading to platelet activation and vasoconstriction. We recommend that in cases of unexplained Raynaud's phenomenon, serology for parvovirus B19 be included in the evaluation.

Pulmonary involvement in adult-onset Still's disease

Adult-onset Still's disease (AOSD) is a rare splenic disorder with an unknown cause. It is not uncommon for AOSD to involve other organs, such as the liver; the kidney; the bone marrow; and, less often, the lungs. In this review, we discuss the pulmonary complications of AOSD. Pulmonary involvement in AOSD usually consists of pleural effusion or transient pulmonary infiltrates, but it may become life threatening if it progresses to the adult respiratory distress syndrome. Chronic conditions, such as restrictive lung disease, have also been reported in patients with AOSD. The only treatment currently available is high-dose steroids, although other agents, such as intravenous immunoglobulin, cyclophosphamide, and azathioprine, have been tried with some success.

Viral arthritis

Identifying viral infections related to rheumatic syndromes and understanding the pathophysiologic mechanisms by which they cause disease are crucial steps to furthering our understanding of the pathogenesis of rheumatic disease. Many common viral infections can induce autoantibody formation. Parvovirus B19 (B19) can cause acute arthritis, and occasionally chronic arthropathy, in infected adults. Persistent B19 infection can be found in synovium of some patients. Antibodies reactive with B19 epitopes can cross react with some autoantigens. Studies of rheumatic syndromes associated with other viral infections, including alphaviruses, rubella, hepatitis C, and retroviruses, suggest differing mechanisms of host interaction with the infectious agents to cause disease.